The invention relates generally to a pleatable filter media for air filtration, and more particularly to a filter media with activated carbon components to convert ozone to O2.
Filter media made of a filtration layer laminated to one or more support (also referred to as “backer”) layers is used in conventional air filtration products, such as filters. The filtration layer can be a charged layer of fibers produced by the meltblown process. The backer layers consist of synthetic nonwoven fibers made in spunbond, dry laid or wet laid processes, and the backer layer can be made of glass fibers. Most backer layers provide little to no resistance to the flow of air due to the large size of the passages extending through the backer (also called “support” and “carrier”) layer.
Filters made of this type of media are widely used in commercial and residential heating, ventilation and air conditioning (HVAC) systems, portable air cleaners, vacuums and other applications. Such conventional filters can remove particulate matter from the air stream forced through them, but they cannot remove ozone (O3) and/or odors.
Ozone is identified, along with particulate matter and formaldehyde, as one of the major air pollutants of indoor air. All pollutants can have an adverse impact on the health of occupants of a dwelling, but ozone is a critical pollutant because it reacts with volatile organic compounds (VOC's) to create secondary particles that are 25-35 nanometers in size.
U.S. Pat. No. 6,099,901 and U.S. Pat. No. 6,302,946 describe methods of fabricating a filter medium capable of odor removal by adding sodium bicarbonate. The filter medium is saturated in a solution of sodium bicarbonate and binder and then dried. The filter material has a basis weight of 125 g/m2 and load of sodium bicarbonate in the range of 2 g/m2.
U.S. Pat. No. 6,024,782 describes a manufacturing process for making adsorptive material using activated carbon, zeolite, silica gel and other adsorbent particles. The manufacturing process consists of spraying adhesive onto a layer of adsorbent particles and forming a multilayered material. Particle diameters for the selected adsorbent are in the range of 0.05 to 3.0 mm, which makes these “coarse” particles.
U.S. Pat. No. 5,942,323 describes a process of making a filter with activated alumina, zeolite, sodium bicarbonate and other materials. The manufacturing process is based on the saturation of the fiber matrix with a water solution of selected substrate.
U.S. Pat. No. 5,942,323 describes a process of making a nonwoven activated carbon fabric with activated carbon fibers ranging from 10 to 75%. U.S. Pat. No. 5,678,247 describes a similar process for making odor-adsorbing clothing.
Other patents of possible relevance include U.S. Pat. No. 7,892,326; U.S. Pat. No. 4,565,727; U.S. Pat. No. 4,495,030; U.S. Pat. No. 6,702,875; and U.S. Pat. No. 6,030,698.